/Engine/Source/Runtime/Engine/Public/AnimationRuntime.h
There may be times when the implementation can pre-calculate data needed for GetPerBoneInterpolationIndex, as the latter is often called multiple times whilst iterating over a skeleton.
virtual [TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< [FPerBoneInterpolationData](API\Runtime\Engine\IInterpolationIndexProvider\FPerBoneInterpolationData) > GetPerBoneInterpolationData ( const [USkeleton](API\Runtime\Engine\Animation\USkeleton) * Skeleton ) const